Background
Prospective multi-institutional study. 30 spine surgeons and 30 radiation oncologists independently scored 30 clinical cases using the Spinal Instability Neoplastic Score (SINS) — a 6-component scoring system developed to standardize assessment of spinal instability in patients with metastatic spinal disease. SINS components: location, pain, bone lesion type, radiographic alignment, vertebral body collapse, posterior element involvement. Fisher CG et al, Spine 2014.
Interventions and follow up
Arm A: N/A — reliability/validation study of a clinical scoring instrument
Primary endpoint: Inter-rater reliability (ICC) of SINS score
mFollow up: N/A
Primary endpoint: Inter-rater reliability (ICC) of SINS score
mFollow up: N/A
Results
SINS scoring: 0–6 (stable), 7–12 (potentially unstable), 13–18 (unstable)
ICC for total SINS score: 0.846 (good agreement)
ICC per component: Pain 0.87; alignment 0.84; bone lesion type 0.76; collapse 0.81; posterior element 0.69
Spine surgery recommendation (SINS ≥13): 93% concordance between raters
ICC for total SINS score: 0.846 (good agreement)
ICC per component: Pain 0.87; alignment 0.84; bone lesion type 0.76; collapse 0.81; posterior element 0.69
Spine surgery recommendation (SINS ≥13): 93% concordance between raters
Adverse events
Main adverse events: N/A — scoring validation study. SINS guides decision between non-operative management and surgical stabilization before or instead of RT.
Conclusions
The SINS has excellent inter-rater reliability across spine surgeons and radiation oncologists, making it a practical tool for standardizing spinal instability assessment. Scores ≥13 reliably identify unstable spines requiring surgical stabilization, while scores ≤6 identify stable spines appropriate for RT without surgery.
Key Limitations
Key Limitations: Validation based on 30 cases scored by 60 raters — does not represent all clinical presentations. The scoring system does not incorporate tumor histology, planned RT dose, or systemic therapy. Reliability in the 7–12 "potentially unstable" range is lower, leaving a gray zone requiring individualized assessment.
Clinical Context
SINS is now standard practice for patients with spinal metastases being considered for RT or SBRT. SINS ≥13: surgical consultation for stabilization before RT. SINS 7–12: multidisciplinary discussion. SINS ≤6: RT can proceed without surgical evaluation. Most international spine SBRT guidelines (AO Spine, ISRC) mandate SINS scoring before SBRT delivery.
References